What was this guy all about? Did he even have a name? In real life I believe he married Adrienne Barbeau from Television's MAUDE after she was married to director John Carpenter.
It was Gene Roddenberry's experiment at SERIOUSLY-color-blind casting. It was his naïve idea that in the future we'd all be so advanced and enlightened that no alien life form (to say nothing of different human races) would be so different as to appear "creepy" to us.
Billy Van Zandt appeared in one movie before ST:TMP, in which he wore a hat, to disguise his oversized forehead. "Jaws 2."
He went on to a successful career as a TV producer, which is how you make enough money to marry Adrienne Barbeau. "Alien Boy" did all right, I'd say.
--Almost forgot: his older brother is Steven Van Zandt. from "The Sopranos" and Bruce Springsteen's E-Street Band.